Competitive Binding of Off‐Flavor Compounds with Soy Protein and β‐Cyclodextrin in a Ternary System: A Model Study

Removal of soy protein (SP)‐bound 2‐nonanone by β‐cyclodextrin (βCD) was studied using an equilibrium dialysis technique. It was observed that in the presence of βCD, a significant (p < 0.05) amount of SP‐bound 2‐nonanone could be removed in a concentration‐dependent manner. Up to 94% of SP‐bound 2‐nonanone was stripped from SP when 6 mM βCD was present in the system. However, in thermodynamic terms, the net standard free energy change for transfer of 2‐nonanone from SP to βCD, i.e., , was essentially zero, implying that the apparent equilibrium binding constant for the formation of βCD–2‐nonanone complex was essentially same as that for the SP–2‐nonanone complex formation in the ternary system. This indicated that stripping‐off of 2‐nonanone from SP by βCD was driven by the mass action ratio. Based on these results, it is shown that βCD can be used effectively for removing SP‐bound off‐flavor carbonyl compounds.